In a natural environment, microbes compete with each other for survival. They not only produce antibiotics to kill other bacteria, but also genetically mutate to protect themselves from the antibiotics produced by other bacteria. That means the presence of an antibacterial resistance (AMR) gene in microbes is ancient and is not a new development. Surely, though, through inappropriate use of antibiotics in animal production and in human medicine, we have disturbed the balance in the microbiological environment and have triggered the AMR gene in various bacteria. Superbugs – microbes with potent AMR activity – have emerged and put human health at risk.
Recently, many global food and restaurant chains have opted to use animal products raised without antibiotics (RWA).
Why are antibiotics needed for poultry?
In intensive poultry farming, the birds undergo tremendous amounts of stress. The stress results in elevated blood levels of the hormone cortisol, which subsequently supresses the bird’s feed intake and growth. Stress also compromises a bird’s immune system, making it susceptible to infectious diseases. The triggered immunological processes utilize nutrients like energy and protein to fight the infection. When a bird is under stress and reducing its feed intake, these nutrients are not sufficiently available to the bird, resulting in reduced performance.
The Role of nutrition in RWA production
Poultry nutrition has an important role to play in RWA production. The feed ingredients used in RWA diets should be of good quality and also be highly digestible. The protein level should be carefully adjusted in the diets so the undigested or unabsorbed protein does not end up in caeca. In caeca, bad bacteria can utilize the undigested nutrients to thrive in the gut. Nutrition in RWA production should be optimized to improve a bird’s gut health and the local immune system.
Several feed supplements, known as alternative growth promoters (AGP), have been incorporated to replace antibiotics. Some of these are outlined below.
- Short-chain fatty acids (SCFA): The SCFA is a good source of energy for cell proliferation of the gut lining. Gut lining acts as the first line of defence against pathogen entry. The SCFA also lower the gut pH, which is not favourable for growth of pathogens. Butyric acid is an example of an SCFA.
- Direct-fed antimicrobials (DFM): Probiotics are DFM that can support gut-friendly microflora and help reduce pathogenic bacterial populations by way of exclusion. Examples include the Lactobacillus and Bifidobacterium species.
- Prebiotics: Prebiotics are products that assist in the proliferation of probiotics and gut-friendly microbes. Examples include yeast-based products and oligosaccharides.
- Feed acidifiers: Organic acids can be added to feed to acidify the feed pH and help control pathogen multiplication in the gut. Examples include citric and formic acids.
- Enzymes: Enzymes help in amplifying the digestibility of feed ingredients and reducing stress on the birds to handle non-nutritive factors of the ingredients. The enzymes also help in reducing the amount of undigested nutrients ending up in the lower gut. Phytases, xylanase, and proteases are all examples of enzymes.
- Essential oils: Essential oils improve digestive secretions, exhibit anti-oxidative and anti-bacterial properties and may stimulate immune response. Examples include oregano oil and thymol.
- Functional fibres: Functional fibres are the soluble component of dietary crude fibre contents, which can be made available for fermentation and utilization by the good microbes in the lower gut for a prebiotic effect. Oligosaccharides are one example of this.
- Mycotoxin binders: Mycotoxins present in poultry feed ingredients may trigger an immune response resulting in inflammation, reduced feed intake and liver damage. Proper testing of feed ingredients should be performed; if in doubt, mycotoxin binders can be added to the feed.
Chick quality and management
In addition to optimizing nutrition, chick or poultry quality at the genetic and hatchery levels is also critically important.
The management practices at the producer level must provide ideal barn conditions in terms of hygiene, water and air quality, etc. Water acidification can be applied to lower the pH of the water to control pathogens. Bird stocking density can be lowered to reduce stress. Farm biosecurity should be tight and frequent barn visits are required to detect any early health challenges.
In a nutshell, poultry production without antibiotics requires a multi-dimensional approach. For RWA production, chick quality, nutrition, and management are the critical areas to be considered for improvement.